Gold alloy clad products



April 12, 1966 FIG I FIGZ FIG4

J- C. LA PLANTE GOLD ALLOY GLAD PRODUCTS Filed Jan. 28, 1965 INVENTOR.

JERRY C. LA PLANTE United States Patent 3,245,764 GOLD ALLOY CLAD PRODUCTS Jerry C. La Plante, Hempstead, Long Island, N.Y., assignor to Alloys Unlimited Inc., Melville, N.Y. Filed Jan. 28, 1965, Ser. No. 428,750 5 Claims. (Cl. 29-196) This application is a continuation-in-part of my copending application entitled, Gold Alloy Cladding, Serial No. 183,384, filed March 29, 1962, now Patent No. 3,199,189, and my copending application entitled, Gold Alloy Cladding, Serial No. 366,885 filed May 12, 1964, which claim processes. This application claims the products.

This invention relates to means and methods of cladding gold alloys of gold germanium, gold silicon and gold silicon germanium on substrates such as nickel, nickel iron, Kovar, molybdenum and related materials.

More specifically, we are referring to gold silicon alloys of 1.5% to 7% silicon and gold germanium from 8% to 15% germanium plus alloys of gold-germanium-silicon from 1.5% to 7% silicon and from 5% to 15% germanium.

It is diflicult to achieve good cladding due to the fact that the gold alloys do not normally form a good bond with the substrate material or even with a gold clad substrate material.

After many unsuccessful experiments, good results were achieved by first leaching the gold alloy to form a porous surface layer of gold. This porous layer then will form a good bond with agold clad substrate, for instance by hot rolling.

Accordingly, a principal object of the invention is to provide new and improved products of clad gold alloys on a substrate metal.

Another object of the invention is to provide a new and improved product comprising a leached gold alloy clad on a metal substrate.

Another object of the invention is to provide new and improved products of clad gold alloys made by the process of leaching the gold alloys to form a porous gold layer and then bonding said porous layer onto a gold clad substrate material.

Another object of the invention is to provide new and improved products of clad gold alloys on metals such as nickel, nickel iron, Kovar, molybdenum, and related materials.

Another object of the invention is to provide new and improved products of leached clad gold alloy foils such as gold germanium, gold silicon and gold germanium onto substrate metals.

Another object of the invention is to provide new and improved products of clad gold silicon of 1.5% to 7% silicon, or gold germanium of 8% to 15% germanium or gold silicon germanium of 1.5% to 7% silicon and 5% to 15 germanium clad onto substrate metals.

These and other objects of the invention will become apparent from the following specification and drawings of w lC FIGURE 1 is a cross sectional view of a gold silicon alloy clad on a metal substrate.

FIGURE 2 is a cross sectional view of a gold germanium alloy clad on a metal substrate.

FIGURE 3 is a cross sectional view of a gold silicon germanium alloy clad on a metal substrate.

FIGURE 4 is a cross sectional view of a gold alloy clad on a metal substrate.

The following unsuccessful experiments were made:

Example 1.-Alloy the particular gold eutectic directly onto the substrate by puddling or melting, using a variety of fiuxing and reducing conditions. Due to the 3,245,764 Patented Apr. 12, 1966 large thermal expansion difference between the gold eutectics and the substrate materials, no adequate bond was created with a resulting cracking and peeling at the interface.

Example 2.-A thin alloy gold cladding was put on the substrate and then the gold alloy was alloyed directly onto the clad surface. This, too, proved unsuccessful for the same reasons.

Example 3.I attempted pressure bonding directly on the substrate. Results again were unsuccessful.

Example 4 .-Pressure bonding plus heat were employed directly on the substrate. This, too, proved unsuccessful.

Example 5 .-Pressure bonding plus heat on the thin gold clad substrate was attempted. Results were again similar.

It became obvious that a bond must be made at a temperature low enough to prevent peeling due to expansion difference. This would entail solid state bonding. Conventional techniques of pressure bonding to the base metal were unsuccessful. Further work with pressure bonding (plus heat) unto pure Au preclad material was only partially successful.

It became apparent that bonding was being prevented by the existence of silicon or germanium rich eutectic phasepresent on the eutectic alloy surface.

This was eliminated by leaching of the alloy material to leach out the silicon or germanium rich phase from the surface by immersion in a proper leaching solution for an appropriate length of time. For example, if the gold silicon alloy is leached for six hours in concentrated HF the surface is depleted of the gold silicon phase to a depth of approximately .0001 inch. This produces a pure gold surface which is readily bonded by standard heat and/or pressure techniques to a gold preclad base material.

The general successful process is as follows:

The gold alloy is leached for six hours in concentrated hydrofluoric acid to deplete the surface of the other materials in the alloy, namely, germanium, silicon or silicon germanium, .to a depth of approximately $4 of a mil, thereby providing a gold rich, probably porous layer.

The alloys referred to are gold silicon of 1.5 to 7% silicon, gold germanium of 8% to 15 germanium, and gold germanium silicon of 1.5 to 7% silicon and 5% to 15% germanium.

The alloy sheet is then bonded to a gold clad substrate by hot rolling, at a temperature below the melting point of the alloy.

In one specific embodiment it was desired to clad gold silicon on Kovar having a gold layer on the other side of the Kovar. The gold layer on the other side of the Kovar is not necessary to the present process. The following steps were taken:

(1) Take a sheet of gold foil .070" thick having convenient dimensions for instance 3" x 6".

2) An ingot of substrate Kovar approximately A" thick having equal dimensions.

(3) A sheet of gold foil .005".0Ol" thick having equal dimensions.

(4) Sandwich the Kovar between the gold sheets and weld around the edges with a heliarc torch.

(5) Heat the assembly to approximately 1300 F. in a reducing atmosphere, for instance of hydrogen.

(6) Roll out the assembly in a rolling mill to approximately .075" thick. The thickness is reduced approximately 25% per pass in the rolling mill.

(7) Anneal at a temperature of 13001400 F. for approximately 1 hour.

(8) Cool in a reducing atmosphere.

(9) To apply the gold silicon take a sheet of gold 3 silicon foil approximately .015" thick of the same size as the rolled out assembly.

(10) Leach the gold silicon foil in hydrofluoric acid or equivalent for approximately six hours. This may be at room temperature as the temperature is not critical. The leaching process removes the silicon along the surface leaving a porous surface layer of gold.

(11) The leached gold silicon foil is then placed on the thin gold clad side of the Kovar of the three-layer as sembly. This four-layer assembly is then rolled at approximately 500 F. down to approximately .009. The porous surface of gold on the alloy forms a good bond with the gold clad Kovar.

In the above example it was desired to sandwich the Kovar between the alloy and a second layer of gold. If the second gold layer is not desired it may be merely eliminated from the process. It does not alTec-t the bonding of the alloy- The same process may be used to bond gold Germanium and gold silicon Germanium as described to nickel, nickel iron, molybdenum and related materials.

FIGURE 1 shows a cross sectional view of a gold silicon sheet or foil 1 having a leached surface clad onto a metal substrate 2 for instance, of the group including nickel, nickel iron, Kovar, molybdenum or other equivalent materials, according to the process described.

FIGURE 2 shows a cross sectional view of a gold germanium sheet 4 of substrate metal of the group in cluding nickel, nickel iron, Kovar, molybdenum or other equivalent materials, according to the process described.

FIGURE 3 shows a cross sectional view of sheet 5 of a gold silicon germanium clad onto a sheet 6 of sub- 1 strate metal of the group including nickel, nickel iron, Kovar, molybdenum or other equivalent materials according to the process described. 1

FIGURE 4 shows a cross sectional view of a sheet of 4 foil 7 of gold alloy clad onto a metal substrate sheet 8 of the group including nickel, nickel iron, Kovar, molybdenum or other equivalent materials according to the process described.

Many modifications may be made by those who desire to practice the invention without departing from the scope thereof ,which is defined by the following claims- ReferencesCited by the Examiner UNITED STATES PATENTS 2,691,816 10/1954 Siegel 29-499 x 2,763,822 9/1956 Frola 6161 148-1.5X 2,969,295 1/1961 Crishal (it al 29 199 X 2,976,181 3/1961 Brookshire 29-199 X 3,025,439 3/1962 Anderson 14s 177 X 3,031,747 5/1962 Green 29-199 X 3,050,667 8/1962 Emeis 29-195 X 3,060,018 10/1962 Desmond 165 DAVID L. RECK, Primary Examiner.

O. MARJAMA, C. N. LOVELL, Assistant Examiners. 

1. THE PRODUCT CONSISTING OF A METAL SUBSTRATE, A GOLD LAYER MECHANICALLY CLAD ON SAID SUBSTRATE, AND A GOLD ALLOY MECHANICALLY CLAD ON SAID GOLD LAYER. 